Fluid control devices include various categories of equipment with control valves and regulators. Such control devices are adapted to be coupled within a fluid process control system such as chemical treatment systems, natural gas delivery systems, etc., for controlling the flow of a fluid therethrough. Each control device includes a body defining a fluid flow-path and a control member assembly for adjusting a dimension of the flow-path. A seat ring is disposed within a throat of the valve body.
The control member assembly typically includes a valve plug assembly having a sealing disk with a sealing surface. When the outlet pressure of the valve body is high, a sealing surface of the sealing disk may sealingly engage the seat ring and close the throat. This prevents the flow of fluid through the regulator. In one example, the sealing disk may be a machined sealing disk used with the regulator, and in another example, the sealing disk may be a molded sealing disk.
More specifically, FIG. 1 depicts one known valve plug assembly 10. In this example, the valve plug assembly 10 is attached to a mounting member, such as a disk holder 12 or a sleeve adapter, for example, which is coupled to a sleeve 14. The valve plug assembly 10 includes a machined, polyurethane sealing disk 16 with a sealing surface 17. The machined sealing disk 16 is coupled to the disk holder 12 by a retainer 18. Screws 20 and washers 22 secure the retainer 18 and the sealing disk 16 to the disk holder 12, for example, but other fasteners may alternatively be used.
FIG. 2 depicts another known valve plug assembly 100. In this example, the valve plug assembly 100 is again attached to a mounting member, such as a disk holder 112, or sleeve adapter, which is coupled to a sleeve 114. The valve plug assembly 100 includes a molded nitrile rubber, such as NBR, sealing disk 116 having a sealing surface 117. The molded sealing disk 116 is coupled to a retainer 130 having a different geometric configuration than the retainer 18 of FIG. 1, for example. Screws 132 and washers 134 again secure the retainer 130 and the sealing disk 116 to the disk holder 112, but other fasteners may again be used. In this example, a seat ring 136 is depicted, which is adapted to be in contact with the sealing surface 117 of the sealing disk 116.
As described, the machined sealing disk 16 depicted in FIG. 1 and the molded sealing disk 116 of FIG. 2 require different retainers 18, 130 be used to secure the sealing disks 16, 116, respectively, to the disk holders 12, 112, for example. In addition, while screws 20, 132 and nuts 22, 134 are both used to secure the retainers 18, 130 to the disk holders 12, 112, often the retainers 18, 130 require a different number and kind of screws 20, 132 and/or nuts 22, 134. Such variations in the retainers 18, 130 and corresponding screws 20, 132 and nuts 22, 134 used for each of the machined sealing disk 16 and the molded sealing disk 116, respectively, makes service of such disks 16, 116 more complicated. Said another way, servicing the sealing disks 16, 116 requires a user to know whether the valve plug assembly 10, 100 includes the machined sealing disk 16 or the molder sealing disk 116 so that a required corresponding retainer and screws and nuts are used, for example.
In addition, and as depicted in FIG. 1, an additional o-ring 24 or similar sealing mechanism is required to be disposed adjacent to the machined sealing disk 16 between the retainer 18 and the disk holder 12. This additional o-ring 24 used with the machined sealing disk 16 is not required or needed with the molded sealing disk 116 depicted in FIG. 2, for example. Thus, a user replacing or servicing the machined sealing disk 16 would need to make sure an additional and proper o-ring 24 or similar sealing mechanism was also included during installation and/or after replacing, repairing and/or servicing the sealing disk 16, for example.